2015-09-28. Dark streaks on Mars are definitely wet, NASA says.

posted Oct 4, 2015, 9:54 AM by Alan Gould
By Eric Hand, Science. For GSS A Changing Cosmos chapter 7. Excerpt: Beginning in 2011, scientists using the Mars Reconnaissance Orbiter (MRO)...found hundreds of streaks, about 5 meters wide, that appear seasonally on steep slopes.... They show up during the warm season, grow hundreds of meters long, and then fade as winter approaches. For many years, the team made the obvious interpretation: ...today on Mars, water was flowing, or at least seeping out of the surface. Salts were expected to be present in the water, because they lower the freezing point of water by tens of degrees, and they also make the water less likely to evaporate in Mars’s barely-there atmosphere. ...Now, they have found evidence for those salts, ...the water could get to the surface streaks either from above, via deliquescence—the absorption of water vapor from the atmosphere—or from below, via an underground aquifer. See the related 5 August 2011 report, “Seasonal flows on warm Martian slopes.” http://news.sciencemag.org/space/2015/09/dark-streaks-mars-are-definitely-wet-nasa-says